Fluoroaluminate (AlF4) compounds

ABSTRACT

Fluoroaluminate compounds of formula M +n  (AlF 4 ) n   -  wherein n is 1 to 3 and M +n  is N(R 2 ) 4 , P(R 2 ) 4 , As(R 2 ) 4 , HN(R 2 ) 3 , H 2  N(R 2 ) 2 , H 3  N(R 2 ), (R 2 ) 3  P═N═P(R 2 ) 3 , S N(R 2 ) 2  ! 3 , ##STR1## (R) 2  N--(C(R) 2 ) k  --N(R) 3 , and ZH m   +m  wherein Z is a base capable of accepting m protons, and various cyclic and aryl groups are disclosed as well as processes for their preparation.

This is a continuation-in-part of application Ser. No. 08/242,480 filed May 13, 1994, abandoned, which is a continuation-in-part of application Ser. No. 07/978,590 filed Nov. 19, 1992 abandoned.

The present invention relates to fluoroaluminate compounds and methods for their preparation.

Many compounds of the general formula M⁺ AlF₄ ⁻ are known wherein the fluoroaluminate Al ion is six-coordinate and wherein M⁺ is a cation, for example, wherein M is potassium, thallium, rubidium, or NH₄. Usually, such compounds are insoluble in nonaqueous media and have extended corner-shared fluoro-bridged network structures in the solid state.

Tetrahedrally coordinated AlF₄ ⁻ compounds have been proposed to exist in a hot melt form or in vapor phase, but upon cooling reassemble into six-coordinate forms. "Tetramethylammonium-fluoroaluminates, -gallates and indates", by P. Bukovec and J. Siftar, Monatsh. Chem. 1975, 106, 483-490, describes the "probable" synthesis of the material N(CH₃)₄ AlF₄ via dissolution of AlF₃ in aqueous HF in the presence of tetramethylammonium fluoride. The material first isolated is N(CH₃)₄ AlF₄ H₂ O which may be dehydrated at 120° C. to give a material of the noted stoichiometry. Evidence for the anhydrous tetrafluoroaluminate as containing a tetrahedral AlF₄ ⁻ anion is based on the simplicity of the IR spectrum.

"Fluoroaluminates of some organic base cations" by A. K. Sengupta and K. Sen., Indian J. Chem., 1979, 17A, 107-108, describes a series of preparations of fluoroaluminate salts of organic cations prepared by dissolution of aluminum hydroxide in aqueous HF in the presence of the organic cation or base. In this case a series of compounds are prepared and their chemical analyses and thermal decomposition behavior reported. The authors claim that the products of thermal decomposition of their compounds are "a mixture of aluminum fluoride and oxide". The fact that oxide is present in the final materials indicates that the materials they have prepared are in all cases mixed fluoro/aquo/hydroxo aluminate species much like the N(CH₃)₄ AlF₄ H₂ O material above.

The aqueous synthetic procedures taught in the above references are not likely to work well for many other compounds. An anhydrous process for preparation of fluoroaluminate compounds is desirable due to its versatility. Additionally, it is desirable to have compounds wherein the four-coordinate form of the AlF₄ ⁻ is retained. Such materials provide low temperature routes to new phases of AlF₃, AlF₃ being a well-documented catalyst for numerous fluorocarbon transformations of industrial importance. Additionally, the solubility of such AlF₄ ⁻ species in non-aqueous (organic) solvents provides a simple route for deposition onto high surface area supports for eventual conversion to well dispersed AlF₃ catalyst phases. The present invention provides such four-coordinate compounds, their precursors, and anhydrous processes for their preparation.

SUMMARY OF THE INVENTION

The present invention comprises a compound of the formula I, M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is an organic cation or polycation other than NMe₄ ⁺, NEt₄ ⁺, N(n-Bu)₄ ⁺, guanidinium H⁺ or PyridineH⁺, and n is an integer from 1 to 3.

In particular the present invention comprises compounds of the above formula wherein M is selected from the group consisting of N(R₂)₄, P(R₂)₄, As(R₂)₄, HN(R₂)₃, H₂ N(R₂)₂, H₃ N(R₂), (R₂)₃ P═N═P(R₂)₃, S N(R₂)₂ !₃, ##STR2## R is hydrogen, C₁ -C₁₀ linear or branched alkyl or aryl; R₂ is C₁ -C₁₀ linear or branched alkyl or aryl;

n is 1; and

k is 1 to 10;

provided that M^(+n) is other than NMe₄ ⁺, NEt₄ ⁺, N(n-Bu)₄ ⁺, guanidinium (H₂ N═C(NH₂)₂)⁺ and pyridinium (C₅ H₆ N)⁺.

The present invention further comprises compounds of formula I, M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is of the form ZH⁺, n is 1, and Z is a base capable of accepting n protons.

The present invention further comprises anhydrous PyH⁺ AlF₄ ⁻ wherein Py is pyridine and which when thermolyzed forms pure AlF₃.

The present invention further comprises a polymer having a repeating unit of the formula (X) or formula (XI). ##STR3## wherein m is 0 or an integer equal to or greater than 1;

n is an integer greater than 1;

Q is NR, O, or S; and

R is H or C₁ -C₆ alkyl.

The present invention further comprises processes for the preparation of compounds of formula M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) and n are defined above. One such process comprises reacting Al(R)₃ with M^(+n) (HF)_(q) F_(n) ⁻ wherein M is an organic cation or polycation; n is an integer from 1 to 3; q is an integer of at least 1; and each R is independently C₁ -C₁₂ alkyl, C₁ -C₁₂ alkoxy, C₁ -C₁₂ enolate, aryl, or C₁ -C₁₂ alkamide.

A second process for the preparation of M^(+n) (AlF₄ ⁻)_(n) wherein n is an integer from 1 to 3, M is an organic cation of formula ZH_(n) ^(+n) and Z is a base capable of accepting n protons, comprises reacting Al(R)₃ wherein each R is independently C₁ -C₁₂ alkyl, C₁ -C₁₂ alkoxy, C₁ -C₁₂ enolate, aryl, or C₁ -C₁₂ alkamide with a solution of HF and Z.

A third process for the preparation of M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is an organic cation or polycation, and n is an integer from 1 to 3 comprises reacting ZH_(m) ^(+m) (AlF₄ ⁻)_(m) with Y, wherein Z is a base capable of accepting m protons wherein m is an integer from 1 to 3, and Y is a proton-accepting base or a phosphorus ylid of formula R₁ R₂ R₃ P═CR₄ R₅ wherein R₁, R₂ and R₃ are each independently linear, branched or cyclic C₁ -C₁₀ alkyl or substituted C₁ -C₁₀ alkyl, C₁ -C₁₀ alkoxy, aryl, aryloxy, heterocyclic, substituted heterocyclic, or together two or more of R₁, R₂ or R₃ may form a ring of 3 to 10 atoms; R₄ and R₅ are each independently hydrogen, linear, branched or cyclic C₁ -C₁₀ alkyl or substituted alkyl, C₁ -C₁₀ alkoxy, aryl, aryloxy, heterocyclic, substituted heterocyclic or R₄ and R₅ together may form a ring of 3 to 10 atoms.

A fourth process for the preparation of M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is an organic cation or polycation, and n is an integer from 1 to 3 comprises reacting ZH_(m) ^(+m) (AlF₄ ⁻)_(m), wherein Z is a base capable of accepting m protons wherein m is an integer from 1 to 3, with M^(+n) (X⁻)_(n) wherein M is an organic cation or polycation other than H⁺ and X is a stronger base than Z.

A fifth process for the preparation of M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is an organic cation or polycation, and n is an integer from 1 to 3 comprises reacting ZH_(m) ^(+m) (AlF₄ ⁻)_(m), wherein Z is a base capable of accepting m protons wherein m is an integer from 1 to 3, with M^(+n) (X⁻)_(n) wherein M^(+n) is an organic cation or polycation other than H⁺ and X⁻ is an anion which forms a compound ZH_(m) ^(+m) (X⁻)_(m) easily separable from the M^(+n) (AlF₄ ⁻)_(n) product.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts the powder X-ray diffraction pattern of M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is H-pyridine and n is 1.

FIG. 2 depicts the X-ray crystal structure of ZH⁺ AlF₄ ⁻ wherein Z is 1,8-bis(dimethylamino)naphthalene.

FIG. 3a depicts the structure of the tetrahedral AlF₄ ⁻ anion as obtained from the x-ray crystal structure of collidinium AlF₄.

FIG. 3b depicts the structure of a chain of octahedral AlF₆ units linked through corner and edge sharing of F as obtained from the x-ray crystal structure of collidinium AlF₄.

FIG. 3c depicts the structure of collidinium cations as obtained from the x-ray crystal structure of collidinium AlF₄.

FIG. 4a depicts the structure of the tetrahedral cation P(C₆ H₅)₄ ⁺ as obtained from the x-ray crystal structure of tetraphenylphosphonium AlF₄.

FIG. 4b depicts the structure of the tetrahedral AlF₄ ⁻ anion as obtained from the x-ray crystal structure of tetraphenylphosphonium AlF₄.

FIG. 5a depicts the structure of the tetrahedral As(C₆ H₅)₄ ⁺ cation as obtained from the x-ray crystal structure of tetraphenylarsonium AlF₄.

FIG. 5b depicts the structure of the tetrahedral AlF₄ ⁻ anion as obtained from the x-ray crystal structure of tetraphenylarsonium AlF₄.

FIG. 6 depicts the powder X-ray diffraction pattern of M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is the triphenylmethylphosphonium cation and n is 1.

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises compounds of formula I

    M.sup.+n (AlF.sub.4.sup.-).sub.n                           I

wherein M^(+n) is an organic cation or polycation other than NMe₄ ⁺, NEt₄ ⁺, N(n-Bu)₄ ⁺, guanidinium H⁺, or PyridineH⁺, and n is an integer from 1 to 3. In particular the present invention includes compounds of formula I wherein M is selected from the group consisting of N(R₂)₄, P(R₂)₄, As(R₂)₄, HN(R₂)₃, H₂ N(R₂)₂, H₃ N(R₂), (R₂)₃ P═N═P(R₂)₃, S N(R₂)₂ !₃, ##STR4## R is hydrogen, C₁ -C₁₀ linear or branched alkyl or aryl; R₂ is C₁ -C₁₀ linear or branched alkyl or aryl;

n is 1; and

k is 1 to 10;

provided that M^(+n) is other than NMe₄ ⁺, NEt₄ ⁺, N(n-Bu)₄ ⁺, guanidinium (H₂ N═C(NH₂)₂)⁺ and pyridinium (C₅ H₆ N)⁺.

The present invention further comprises compounds of the formula I, M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is of the form ZH_(m) ^(+m), n is 1, m is an integer of 1 to 3, and Z is a base capable of accepting m protons.

The present invention further comprises PyH⁺ AlF₄ ⁻ wherein Py is pyridine and which when thermolyzed forms pure AlF₃.

In the above recitations and the processes of the present invention, the term "alkyl" denotes straight chain or branched alkyl; e.g., methyl, ethyl, n-propyl, i-propyl, or the different butyl, pentyl, hexyl, etc. isomers. Cyclic alkyls include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. The abbreviation Me denotes methyl, Et denotes ethyl, and n-Bu denotes n-butyl.

"Alkenyl" denotes straight chain or branched alkenes; e.g., 1-propenyl, 2-propenyl, and the different butenyl, pentenyl, hexenyl, etc. isomers. "Dienyl" denotes polyenes having two double bonds such as 1,3-hexadiene and the like.

"Alkoxy" denotes methoxy, ethoxy, n-propyloxy, isopropyloxy and the different butoxy, pentoxy, hexyloxy, etc. isomers.

"Aryl" includes aromatic hydrocarbons such as benzene, substituted benzene, such as toluene, aniline, benzoic acid, halobenzene, nitrobenzene, etc., naphthalene, or substituted naphthalene.

"Heterocyclic" denotes 5- or 6-membered rings containing 1 to 3 nitrogen, oxygen, or sulfur atoms or combinations thereof such as furanyl, thiofuranyl, tetrahydrofuranyl, thiopheneyl, pyrrolyl, pyrazolyl, triazolyl, dithiolyl, oxathiolyl, oxazolyl, thiazolyl, dioxazolyl, oxathiazolyl, pyranyl, pyronyl, pyridinyl, pyrimindinyl, pyrazinyl, triazinyl, oxazinyl, oxathiazinyl, imidazolyl, etc. Preferred in the compounds and processes of the present invention are pyridinyl, furanyl, tetrahydrofuranyl, pyranyl, imidazolyl or thiopheneyl.

Substituted alkyl includes C₁ -C₁₀ alkyl having at least one substituent. Suitable substituents include hydrogen, C₁ -C₁₀ alkyl, C₂ -C₁₀ alkenyl, C₂ -C₁₀ alkynyl, or aryl.

Substituted heterocyclic includes heterocyclic as defined above having at least one substituent. Suitable substituents include hydrogen, C₁ -C₁₀ alkyl, C₂ -C₁₀ alkenyl, C₂ -C₁₀ alkynyl, or halogen.

"Polycation" denotes multiple singly charge atoms linked to form a cation having a net charge greater than one. It is not meant to indicate multiple charges on individual atoms making up the cation.

Preferred cations include trialkylammonium, tetraalkylammonium wherein alkyl is other than methyl, ethyl and butyl, tetraalkylphosphonium and mixed alkyl- and aryl-phosphonium where the P atom is bound to four different carbon atoms, and analogous arsonium compounds. Also preferred in addition to the above are pyrilium and substituted pyrilium, thiopyrilium and substituted thiopyrilium, and bis(triphenylphosphine)iminium cations, as well as polyvinylpyridinium and polyalkyleneammonium polycations.

Preferred compounds are: triphenylmethylphosphonium tetrafluoroaluminate, tetraethylphosphonium tetrafluoroaluminate, tetraphenylphosphonium tetrafluoroaluminate, tetraphenylarsonium tetrafluoroaluminate, tetrapropylammonium tetrafluoroaluminate or 1,8-bisdimethylaminonapthalenium tetrafluoroaluminate.

The present invention also comprises compounds of formula M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is of the form ZH_(n) ^(+n) wherein n is 1 and wherein Z is a base capable of accepting n protons, preferably amine, pyridine or ylid. Preferred are such compounds wherein Z is pyridine, 1,8-bis(dimethylamino)naphthalene, 2,4,6-trimethylpyridine (collidine), or 2,6-dimethylpyridine (lutidine). Also preferred is anhydrous PyH⁺ AlF₄ ⁻ wherein Py is pyridine and which when thermolyzed at a temperature of from about 285° C. to about 450° C. forms pure AlF₃. Pure is used herein to mean that the AlF₃ is uncontaminated with Al₂ O₃ as detectable by X-ray diffraction.

The compounds of formula I can be prepared as described below in rigorously pure and anhydrous form. Depending upon the choice of M^(+n), the compounds may be freely soluble in nonaqueous solvents, and the AlF₄ ⁻ anion may be four-coordinate with no bridging fluorides nor additional ligating groups.

The compounds of formula I are useful for the preparation of pure AlF₃ in several of its crystalline phases such as alpha, beta, eta, theta, or kappa, without oxide or hydroxide contamination or incorporation. AlF₃ results from the anhydrous thermal decomposition of compounds of formula I at temperatures ranging from about 285° C. to about 450° C. depending upon the exact composition of the organic cation or polycation. A. K. Sengupta and K. Sen (Indian J. Chem. 1979, 17A, 107-108) briefly describe the thermolysis of several fluoroaluminate salts of organic cations to "a mixture of aluminum fluoride and oxide", the oxide arising from water or hydroxide present in their "fluoroaluminate" materials. Bulk AlF₃ is useful as a solid-state catalyst for chlorofluorocarbon isomerization and fluorination, and high surface area AlF₃ dispersed onto carbon, organic, or inorganic supports may be a useful catalyst for these or other reactions. Embodiments of the latter are described by U.S. Pat. No. 5,171,798 issued Dec. 15, 1992 to McDaniel et al., wherein fluoroaluminum species generated on a support of alumina were subsequently treated with e.g., chromium to obtain active olefin polymerization catalysts. Routes to such high surface area AlF₃ phases dispersed on inorganic supports are provided by the solubility of AlF₄ ⁻ species of the formula I type in non-aqueous solvents. Suitable non-aqueous solvents include solvents such as methanol, ethanol, pyridine, acetonitrile, acetone, tetrahydrofuran, dimethylsulfoxide, dimethylformamide, formamide, dichloromethane or chloroform. The AlF₄ ⁻ species are readily deposited onto high surface area supports and subsequent thermolysis converts the AlF₄ ⁻ species to well-dispersed AlF₃ phases.

The present invention further comprises a polymer comprising repeating units having the formulae (X) or (XI) ##STR5## wherein m is 0 or an integer equal to or greater than 1; n is an integer greater than 1; Q is NR, O or S; and R is H or C₁ -C₆ alkyl. Preferred polymers are polyethylene containing pendant quaternary ammonium groups and polystyrene containing occasional incorporated polyvinyl pyridinium groups. The polymers of the present invention are prepared by anion exchange reactions known to those skilled in the art.

In a preferred example, a commercially available anion exchange resin in its halide (X⁻ where X=Cl, Br, I) form may be packed in a vertical chromatography column using methanol solvent. A solution of collidineH⁺ AlF₄ ⁻ in methanol may be added to the top of the column and the solution drained through the column. As the AlF₄ ⁻ solution travels through the column it will displace the original halide ion (X⁻) from the anion exchange resin so that the column eluent will consist of collidineH⁺ X⁻ while the column will become transformed to the desired AlF₄ ⁻ form. The progress of this transformation may be monitored by analyzing the effluent for halide ion (X⁻). When no further halide is present the exchange of AlF₄ ⁻ for X⁻ on the resin is complete generating polymers of repeating units of formula (X) or (XI).

The utility of the AlF₄ ⁻ exchanged resin is in its ability to be transformed into the corresponding AlF₃ phase upon mild thermal treatment (300°-400° C.) in an inert atmosphere (nitrogen, argon, helium or vacuum) to eliminate RF (where R is H or alkyl or aryl originating from the resin). The resulting composite material of AlF₃ dispersed on an organic polymeric resin is useful as a high surface area form of the known fluorocarbon transformation catalyst AlF₃.

The present invention further comprises the processes of Equations 1 to 5 useful for the preparation of compounds of formula I as shown in Scheme 1. ##EQU1##

In Equation 1 an aluminum source, Al(R)₃, wherein each R is independently C₁ -C₁₂ alkyl, C₁ -C₁₂ alkoxy, C₁ -C₁₂ enolate, aryl, or C₁ -C₁₂ alkamide is reacted with M^(+n) (HF)_(q) F_(n) ⁻ wherein M^(+n) is an organic cation or polycation as defined in formula I, q is greater than or equal to 1, and n is an integer from 1 to 3. Such starting materials can be made according to the procedures of Colton, R., et al. Aust. J. Chem. 42, 1605-9, 1989. The reaction is conducted in a solvent which is unreactive with Al(R)₃ or which undergoes only coordination to Al(R)₃ such as ethers, tertiary amines, or nitrogen-containing heterocyclic compounds. Preferred is pyridine. The mole ratio of Al(R)₃ to q in M^(+n) (HF)_(q) F_(n) ⁻ is at least 1:3. The reaction is conducted at a temperature of from about -100° C. to about 150° C. depending upon the solvent employed. Preferably the reaction is conducted at a temperature of from about -40° C. to 60° C. Use of an inert atmosphere such as nitrogen or argon is required to exclude oxygen and water. The reaction is conducted at ambient pressure or under a vacuum. The preferred pressure is from about 0.01 to 5 atm (10³ to 5×10⁵ Pa). Agitation is optional but preferred. The desired product, M^(+n) (AlF₄ ⁻)_(n) can be isolated using routine procedures such as filtration or crystallization.

For the process of Equation 2, an aluminum source Al(R)₃, wherein each R is independently C₁ -C₁₂ alkyl, C₁ -C₁₂ alkoxy, C₁ -C₁₂ enolate, aryl or C₁ -C₁₂ alkamide, such as trimethylaluminum is mixed with reagent Z, under an inert atmosphere and anhydrous HF added. Z is a base capable of accepting n protons wherein n is an integer from 1 to 3. Such starting materials are commercially available or are prepared according to Colton above. Examples of suitable reagent Z include pyridine, triethylamine, substituted pyridines and substituted amines. The mole ratio of Al(R)₃ to HF employed is at least about 1:4. Suitable solvents include amines, phosphines, arsines, nitrogen containing heterocyclic compounds or Z as defined above. Preferred for use in this process are pyridine, substituted pyridine or trialkylamines. The reaction is conducted at a temperature of from about -100° C. to about 150° C., preferably at -40° C. to 60° C. depending upon the solvent used. Use of ambient pressure or a vacuum is employed, preferably from about 0.01 to 5 atm (10³ to 5×10⁵ Pa). An inert atmosphere such as nitrogen, argon, or helium is employed to maintain an environment free of oxygen, water or carbon dioxide. Agitation is optional but preferred. After stirring, the reaction mixture is left to stand at ambient temperature and the desired ZH_(m) ^(+m) (AlF₄ ⁻)_(m) product may precipitate out and can be isolated by filtration or other equivalent means.

ZH_(m) ^(+m) (AlF₄ ⁻)_(m), prepared as in the process of Equation 2, can be employed in the process of Equation 3. The Equation 3 process comprises reacting ZH_(m) ^(+m) (AlF₄ ⁻)_(m) with Y, wherein Z is a base capable of accepting m protons wherein m is an integer from 1 to 3, and Y is a base capable of accepting n protons wherein n is an integer from 1 to 3 or a phosphorus ylid, and Y is more basic than Z. In Equation 3, Y is a proton-accepting base such as pyridine, amine, or a phosphorus ylid of formula R₁ R₂ R₃ P═CR₄ R₅ wherein

R₁, R₂ and R₃ are each independently linear, branched or cyclic C₁ -C₁₀ alkyl or substituted C₁ -C₁₀ alkyl, alkylene, C₁ -C₁₀ alkoxy, aryl, aryloxy, heterocyclic, substituted heterocyclic, or together two or more of R₁, R₂ or R₃ may form a ring of 3 to 10 atoms;

R₄ and R₅ are each independently hydrogen, linear, branched or cyclic C₁ -C₁₀ alkyl or substituted C₁ -C₁₀ alkyl, alkylene, C₁ -C₁₀ alkoxy, aryl, aryloxy, heterocyclic, substituted heterocyclic or R₄ and R₅ together may form a ring of 3 to 10 atoms; and

Y is a stronger base than Z.

Substituted alkyl, heterocyclic, and substituted heterocyclic are as previously defined.

Examples of suitable Z include pyridine, 2,4,6-tri-methylpyridine, 1,8-bis(dimethylamino)naphthalene, 2,6-dimethylpyridine and the like. The mole ratio of Y to ZH_(m) ^(+m) (AlF₄ ⁻)_(m) employed is m, wherein m is an integer of 1 to 3 or greater. Suitable solvents include chlorocarbons, ethers, amines, nitrogen-containing heterocyclic compounds or Y as defined above. Preferred solvents are tetrahydrofuran and substituted pyridines. The reaction is conducted at a temperature of from about -100° C. to about 150° C., preferably from about -40° C. to 60° C. depending upon the solvent employed. Exclusion of water vapor, oxygen and carbon dioxide is required if they would react with Y or Z. Use of an inert atmosphere such as nitrogen, argon or helium is preferred. The reaction is conducted at ambient pressure or under vacuum, preferably from about 0.01 to 5 atm (10³ to 5×10⁵ Pa). Use of vigorous agitation is preferred.

It has been found that it is particularly advantageous to use bases as reagent Y in Equation 3 such that their conjugate acids YH⁺ are incapable of forming strong hydrogen bonds to the fluoroaluminate anion, as the resulting compounds YH⁺ AlF₄ ⁻ then tend to be freely soluble in organic solvents. Two particular examples are 1,8-bis(dimethylamino)naphthalene where the conjugate acid, even though possessing NH groups, is a very weak hydrogen-bonding participant; and (C₂ H₅)₃ P═CHCH₃, where the conjugate acid has hydrogen only bonded to carbon and does not normally participate in hydrogen-bonding. Most ylid compounds of phosphorus, arsenic, sulfur, nitrogen, and other elements are suitable to serve as base Y in Equation 3 and likewise provide conjugate acid cations YH⁺ that form only weak hydrogen bonds to fluoroaluminate anions.

A further process for the preparation of M^(+n) (AlF₄ ⁻)_(n) is the reaction of Equation 4. ZH_(m) ^(+m) (AlF₄ ⁻)_(m), prepared as in Equation 2, wherein Z is a base capable of accepting m protons wherein m is an integer of 1 to 3, is reacted in a simple ion metathesis with M^(+n) (X⁻)_(n) wherein M^(+n) is an organic cation or polycation as defined in formula I and X⁻ is a stronger base than Z. Suitable cations for M⁺ include, for example, As(C₆ H₅)₄ ⁺, P(C₆ H₅)₄ ⁺, P(C₆ H₅)₃ CH₃ ⁺, N(C₂ H₅)₄ ⁺ and the like. Suitable anions for X⁻ include 2,6-dimethylphenolate, trimethylacetate, and the like. The mole ratio of M^(+n) (X⁻)_(n) to ZH_(m) ^(+m) (AlF₄ ⁻)_(m) is preferably m:n. An excess of either can be used. The reaction is conducted in a solvent such as a halocarbon, ether, alcohol, ketone, amine, or heterocyclic nitrogen compound. Preferred solvents are tetrahydrofuran, methanol, acetone, dichloromethane, or pyridine. The temperature employed depends upon the solvent used and can range from about -100° C. to about 150° C., preferably -40° C. to 60° C. The pressure employed can be ambient or a vacuum used, and is preferably from about 0.01 to about 5 atm (10³ to 5×10⁵ Pa). Water vapor should be excluded so the reaction is conducted in an inert atmosphere such as nitrogen, argon, or helium. The desired product, M^(+n) (AlF₄ ⁻)_(n) is isolated by conventional means such as crystallization or filtration.

A further process for the preparation of M^(+n) (AlF₄ ⁻)_(n) is the reaction of Equation 5 comprising reacting ZH_(m) ^(+m) (AlF₄ ⁻)_(m) wherein Z is a base capable of accepting m protons wherein m is an integer of 1 to 3, with M^(+n) (X⁻)_(n) wherein M^(+n) is an organic cation or polycation as defined in formula I and X⁻ is a halide or other anion, such as SCN⁻, N₃ ⁻, OCN⁻, CF₃ SO₃ ⁻, ClO₄ ⁻, NO₃ ⁻, or SO₄ ²⁻. The reaction conditions are substantially the same as those described for Equation 4 except that X⁻ is not a stronger base than Z, but can be of comparable or lesser strength.

The following examples are representative of the present invention. The desired product, M^(+n) (AlF₄ ⁻)_(n), is isolated by conventional means such as crystallization or filtration.

EXAMPLE 1 Preparation of H-pyridine⁺ AlF₄ ⁻

Under an N₂ atmosphere in a drybox, 0.216 g trimethylaluminum (CAUTION| This material is pyrophoric in air and reacts vigorously with many solvents, including alcohols, ethers, and pyridine) was dissolved in 20 mL dry pyridine in a plastic beaker. To this solution was added 0.37 g of HF-pyridine solution (separately determined to have the approximate composition HF(pyridine)0.135, equivalent weight 30.7). After the vigorous reaction had subsided the mixture was stirred for 1 hour. Additional pyridine (20 mL) was added and the mixture was transferred to a glass vessel. After standing 3 days at ambient temperature the mixture was filtered and the insolubles dried in vacuum at ambient temperature, yield 0.39 g. The resulting material contained excess solvent. Anal. Calcd. for H(pyridine)₁.3 AlF₄ : C, 37.75%; H, 3.65%; N, 8.80%. Found (Galbraith): C, 37.77, 37.37%; H, 3.57, 3.67%; N, 8.47, 8.69%. The X-ray powder diffraction pattern of a typical sample is shown in FIG. 1. The corresponding data is in Table I.

                  TABLE I                                                          ______________________________________                                         Generator Settings                                                                            40 kV, 30 mA                                                    CU alpha1, 2 wavelengths                                                                      1.540598, 1.544435 Ang                                          Step size, sample time                                                                        0.20 deg, 0.50 s, 25.00 s/deg                                   Monochromator used                                                                            Yes                                                             Divergence slit                                                                               Automatic (specimen length: 12.5 mm)                            Analysis program number                                                                       1                                                               Peak angle range                                                                              2.000-60.000 deg                                                Peak position criterion                                                                       Top of smoothed data                                            Number of peaks in file                                                                       33 (Alpha1: 33, Amorphous: 0)                                   ______________________________________                                         Peak  Angle    Width   Peak  Backg D spac I/Imax                               No.   (deg)    (deg)   (cts) (cts) (Ang)  (%)                                  ______________________________________                                         1     2.272    0.24    22    27    38.8774                                                                               1                                    2     9.283    0.28    2343  99    9.5276 100                                  3     10.258   0.14    1459  93    8.6240 62                                   4     15.422   0.20    64    82    5.7455 3                                    5     17.372   0.16    1129  87    5.1048 48                                   6     18.445   0.08    219   89    4.8103 9                                    7     18.715   0.14    262   89    4.7415 11                                   8     20.630   0.10    408   95    4.3055 17                                   9     22.357   0.18    353   99    3.9766 15                                   10    23.872   0.20    645   103   3.7275 28                                   11    25.650   0.06    339   107   3.4731 14                                   12    26.057   0.14    581   109   3.4197 25                                   13    27.780   0.08    289   113   3.2115 12                                   14    29.455   0.12    161   118   3.0325 7                                    15    30.117   0.20    102   118   2.9673 4                                    16    31.105   0.10    231   122   2.8753 10                                   17    34.410   0.06    112   129   2.6064 5                                    18    34.745   0.20    207   129   2.5820 9                                    19    35.878   0.48    48    129   2.5030 2                                    20    37.275   0.24    137   129   2.4124 6                                    21    38.048   0.08    159   129   2.3651 7                                    22    39.627   0.20    119   129   2.2744 5                                    23    41.950   0.16    98    129   2.1537 4                                    24    42.610   0.24    66    129   2.1219 3                                    25    44.735   0.12    135   143   2.0259 6                                    26    45.190   0.20    77    148   2.0065 3                                    27    46.768   0.10    27    148   1.9425 1                                    28    48.055   0.12    196   145   1.8934 8                                    29    51.140   0.24    56    148   1.7862 2                                    30    53.180   0.12    48    133   1.7224 2                                    31    53.658   0.24    45    133   1.7082 2                                    32    55.320   0.64    24    131   1.6607 1                                    33    57.472   0.24    25    1274  1.6035 1                                    ______________________________________                                    

EXAMPLE 2 Preparation of BH⁺ AlF₄ ⁻, B=1,8-bis(dimethylamino)naphthalene

H-pyridine⁺ AlF₄ ⁻ (0.19 g) prepared as in Example 1 and 1,8-bis(dimethylamino)naphthalene (0.21 g) were combined in a ca. 2 mL dry acetonitrile, under nitrogen in a drybox. The mixture was stirred and rapidly became a solution. Diethyl ether was then slowly added until precipitation began, at which time the mixture was filtered and the initial precipitate was discarded. More diethyl ether was added to the solution, eventually precipitating 0.19 g white solid, mp. 260° C. Anal. Calcd. for C₁₄ H₁₉ N₂ Al₁ F₄ : C, 52.83%; H, 6.02%; N, 8.80%; Al, 8.48%; F, 23.88%. Found (Galbraith): C, 52.61, 52.87%; H, 6.06, 5.78%; N, 8.74, 8.80%; Al, 8.73, 8.40%; F, 18.79, 18.70%. The fluorine analysis is poor owing perhaps to incomplete degradation of AlF₄ ⁻ during the analytical procedure. IR (Nujol) AlF₄ ⁻ at 790/cm. NMR (0.002M in CD₃ CN): ¹⁹ F, -194.2 ppm, 6 lines, J=38 Hz; ²⁷ Al, 49.2 ppm, binomial quintet, J=38 Hz. A single crystal, grown from CH₂ Cl₂ /toluene solution, was used for an X-ray structure determination. The resulting data are shown in Table II and FIG. 2.

The X-ray crystal analysis was as follows: ##STR6## CRYSTAL DATA

AlF₄ N₂ C₁₄ H₁₉, from CH₂ Cl₂ /toluene, colorless, square plate, ˜0.34×0.10×0.54 mm, triclinic, P1 (No. 2), a=8.081(1), b=8.307(1), c=12.375(1) Å, α=82.84(1), β=76.16(1), γ=79.13(1)°, from 47 reflections, T=-100° C., V=789.4 Å³, Z=2, FW=318.30, Dc=1.339 g/cc, μ(Mo)=1.58 cm⁻¹.

DATA COLLECTION AND TREATMENT

Syntex R3 diffractometer, MoKα radiation, 7858 data collected, 5.0°≦2θ≦55.0°, maximum h,k,l=10 10 31, data octants=+++, ++-, +-+, +--, -++, -+-, ω scan method, scan width=1.50°ω, scan speed=3.90°-11.70°/min., typical half-height peak width=0.70°ω, 6.1% variation in azimuthal scan, no absorption correction, 1981 unique reflections with I≧3.0 σ(I).

SOLUTION AND REFINEMENT

Structure solved by direct methods (SHELXS), refinement by full-matrix least squares on F, scattering factors from Int. Tables for X-ray Crystallography, Vol. IV, including anomalous terms for Al, biweight α σ² (l)+0.0009I² !^(-1/2), (excluded 2), refined anisotropic: all non-hydrogen atoms, isotropic: H, 293 parameters, data/parameter ratio=6.75, final R=0.051, Rw=0.048, error of fit=1.70, max Δ/σ=0.12, largest residual density=0.27 e/Å³, near F1.

Results

The proposed crystal structure with an isolated, monomeric AlF₄ anion was confirmed even though the anion was two-fold disordered around the Al(1)-F(1) axis. F(1) was fully occupied: the remainder of the fluorines were assigned occupancies of 0.5. F(1) was also unique in that it formed the closest contact with the proton, H(1). The distance, 2.77 Å, was too long to be considered a real hydrogen bond, the approach of the anion to the proton being hindered by the cluster of methyl groups. All of the hydrogen atoms were refined. Crystals of this compound were invariably twinned. The crystal selected for this study had a single set of diffraction spots when photographed but generally had broad omega scans and some split peaks. In addition, one low-angle peak had sufficient intensity to suggest that the cell should be doubled. The cell was doubled during the data collection but no other reflections with significant intensity were found. The intensity was probably diffuse scattering related to the disordered anion.

                  TABLE II                                                         ______________________________________                                         Fractional Coordinates (X10000)                                                and Isotropic Thermal Parameters                                               ATOM   X          Y          Z        BISO                                     ______________________________________                                         Al(1)  3342.8(11) 2601.4(12) -1791.2(7)                                                                              3.1(1)'                                  F(1)   3543(3)    2960(3)    -553(2)  7.8(1)'                                  F(2')  5040(8)    2716(12)   -2673(5) 9.9(3)'                                  F(2")  4929(9)    1435(10)   -2592(6) 10.7(3)'                                 F(3')  1658(8)    3708(9)    -2083(4) 8.0(2)'                                  F(3")  3303(14)   4424(6)    -2490(5) 11.1(3)'                                 F(4')  2895(11)   730(6)     -1519(5) 9.5(3)'                                  F(4")  1617(8)    1967(15)   -1797(5) 11.1(4)'                                 N(1)   685(3)     1749(3)    1764(2)  2.5(1)'                                  N(2)   2896(3)    3451(3)    2033(2)  3.0(1)'                                  C(1)   701(4)     2507(3)    3632(2)  2.9(1)'                                  C(2)   -153(3)    1845(3)    2948(2)  2.7(1)'                                  C(3)   -1658(4)   1258(4)    3389(3)  3.6(1)'                                  C(4)   -2423(5)   1314(4)    4540(3)  4.3(1)'                                  C(5)   -1621(5)   1876(4)    5215(3)  4.2(1)'                                  C(6)   -42(4)     2459(3)    4801(2)  3.5(1)'                                  C(7)   822(5)     3008(4)    5518(3)  4.4(1)'                                  C(8)   2309(6)    3604(4)    5118(3)  4.8(1)'                                  C(9)   3014(5)    3752(4)    3966(3)  4.0(1)'                                  C(10)  2228(4)    3227(3)    3244(2)  3.1(1)'                                  C(11)  1549(5)    51(4)      1523(3)  4.1(1)'                                  C(12)  -489(4)    2437(5)    1009(3)  3.8(1)'                                  C(13)  4765(4)    2773(6)    1683(3)  4.8(1)'                                  C(14)  2492(6)    5191(5)    1603(3)  4.2(1)'                                  H(1)   1966(50)   2654(48)   1695(31) 8.8(11)                                  H(3)   -2157(35)  780(34)    2909(23) 3.6(7)                                   H(4)   -3618(45)  868(41)    4811(27) 6.0(8)                                   H(5)   -2161(41)  1907(39)   6003(29) 5.4(8)                                   H(7)   311(44)    2861(43)   6298(31) 6.3(9)                                   H(8)   2776(41)   3998(39)   5551(28) 5.1(8)                                   H(9)   3974(38)   4289(37)   3662(24) 4.0(7)                                   H(11)  2133(37)   44(34)     798(26)  3.4(7)                                   H(11') 645(38)    -691(38)   1635(23) 4.3(7)                                   H(11") 2436(46)   -263(44)   1961(29) 5.8(9)                                   H(12)  166(37)    2520(33)   297(25)  3.5(7)                                   H(12') -1083(44)  3591(46)   1185(27) 5.7(9)                                   H(12") -1400(42)  1808(38)   1040(24) 4.7(8)                                   H(13)  5075(36)   2801(35)   861(28)  4.3(7)                                   H(13') 4958(43)   1536(48)   2056(29) 5.9(9)                                   H(13") 5354(42)   3399(40)   1957(27) 5.3(8)                                   H(14)  2892(37)   5222(35)   817(27)  4.2(7)                                   H(14') 3008(43)   5898(44)   1939(28) 5.8(9)                                   H(14") 1199(49)   5607(41)   1826(27) 5.5(9)                                   ______________________________________                                    

EXAMPLE 3 Preparation of CollidineH⁺ AlF₄ ⁻

Inside a nitrogen filled glove box, 10 g of the material pyridineH⁺ AlF₄ ⁻ prepared as in Example 1 was slurried into 50 mL (excess) dry collidine (2,4,6-trimethylpyridine). This mixture was heated with stirring to 120° C. at which point the white solid completely dissolved to give a pale yellow solution. Stirring was ceased and the solution allowed to slowly cool whereupon colorless needles of the desired compound crystallized from solution as a dense white mat. The solid was collected by filtration and washing with THF then suction dried. Yield=11.5 g (94%). IR (KBr) AlF₄ ⁻ at 783 cm⁻¹ also AlF species at 687, 629, 603, 520 cm⁻¹. ²⁷ Al 51.6 ppm, quintet, J=38 Hz. Solid state ¹⁹ F MAS-NMR shows two resonances at -155 ppm (broad) and -187.8 ppm (sharp). A single crystal grown from the above solution in collidine was used for a single crystal structure determination. Crystal data: AlF₄ NC₈ H₁₂ from hot collidine, colorless, needle, 0.05×0.05×0.70 mm, orthorhombic, Pbcn (#60), a=29.673(6), b=16.644(3), c=12.439(3) Å, T=-100° C., V=6143.3 Å³, Z=24, FW=225.17, Dc=1.461 g/cc, μ(Mo)=2.10 cm⁻¹. All non-hydrogen atoms refined anisotropic, 526 parameters, data/parameter ratio=6.46, final R=0.044, Rw=0.036, error of fit=1.24. Atomic coordinates are listed in Table III while the structure is depicted in FIG. 3. The structure showed both the tetrahedral AlF₄ ⁻ anions (FIG. 3a) and an infinite polymeric chain of octahedral AlF₆ units linked through corner and edge sharing of F (FIG. 3b) and stabilized by hydrogen bonded collidinium cations (FIG. 3c).

                  TABLE III                                                        ______________________________________                                         Fractional Coordinates (X10000) and                                            Isotropic Thermal Parameters                                                   ATOM     X        Y          Z      BISO                                       ______________________________________                                         Al(1)    5000     5000       0      1.2(1)'                                    Al(2)    5000     5875(1)    2500   1.1(1)'                                    Al(3)    5000     4137(1)    2500   1.2(1)'                                    Al(4)    5000     10381(1)   2500   3.5(1)'                                    Al(5)    2339     5875(1)    -542(1)                                                                               3.2(1)'                                    F(1)     4412     5006(1)    -146(1)                                                                               1.6(1)'                                    F(2)     4960(1)  5802(1)    1032(1)                                                                               1.4(1)'                                    F(3)     4954(1)  4217(1)    1041(1)                                                                               1.5(1)'                                    F(4)     4563(1)  6576(1)    2566(1)                                                                               1.8(1)'                                    F(5)     4606(1)  5008(1)    2557(1)                                                                               1.3(1)'                                    F(6)     4565(1)  3432(1)    2587(1)                                                                               1.7(1)'                                    F(7)     5228(1)  9791(1)    1581(2)                                                                               6.5(1)'                                    F(8)     4622(1)  10964(2)   1927(2)                                                                               6.0(1)'                                    F(9)     2061(1)  5199(1)    -1266(2)                                                                              4.1(1)'                                    F(10)    1974(1)  6514(1)    2(2)   6.6(1)'                                    F(11)    2680(1)  6402(1)    -1325(2)                                                                              4.9(1)'                                    F(12)    2644(11) 5430(2)    383(2) 6.9(1)'                                    N(1)     3728(1)  4431(2)    -1239(2)                                                                              1.7(1)'                                    N(11)    3874(1)  7388(2)    1796(2)                                                                               2.1(1)'                                    N(21)    4324(1)  2129(2)    3709(2)                                                                               2.0(1)'                                    C(2)     3462(1)  4813(2)    -1945(3)                                                                              1.9(1)'                                    C(3)     3062(1)  4460(2)    -2239(3)                                                                              2.2(1)'                                    C(4)     2936(1)  3720(2)    -1819(3)                                                                              2.2(1)'                                    C(5)     3227(1)  3349(2)    -1112(3)                                                                              2.2(1)'                                    C(6)     3626(1)  3708(2)    -816(3)                                                                               2.0(1)'                                    C(7)     3610(2)  5610(3)    -2367(5)                                                                              3.5(1)'                                    C(8)     2492(2)  3359(3)    -2124(4)                                                                              3.4(1)'                                    C(9)     3962(1)  3342(2)    -76(3) 2.7(1)'                                    C(12)    3622(1)  7042(2)    1027(3)                                                                               2.1(1)'                                    C(13)    3229(1)  7415(2)    739(3) 2.5(1)'                                    C(14)    3090(1)  8118(2)    1239(3)                                                                               2.6(1)'                                    C(15)    3370(1)  8446(2)    2009(3)                                                                               2.4(1)'                                    C(16)    3767(1)  8078(2)    2286(3)                                                                               2.3(1)'                                    C(17)    3793(2)  6279(3)    552(4) 3.1(1)'                                    C(18)    2646(2)  8502(4)    950(5) 4.5(2)'                                    C(19)    4083(2)  8392(4)    3117(5)                                                                               4.3(2)'                                    C(22)    4577(1)  1876(2)    4542(3)                                                                               2.3(1)'                                    C(23)    4440(1)  1199(2)    5083(3)                                                                               3.0(1)'                                    C(24)    4051(1)  795(2)     4788(3)                                                                               2.6(1)'                                    C(25)    3809(1)  1080(2)    3930(3)                                                                               2.6(1)'                                    C(26)    3949(1)  1753(2)    3372(3)                                                                               2.3(1)'                                    C(27)    4992(2)  2340(3)    4800(4)                                                                               4.0(1)'                                    C(28)    3916(2)  43(3)      5373(4)                                                                               4.3(1)'                                    C(29)    3721(2)  2083(3)    2408(5)                                                                               4.0(1)'                                    H(1N)    3958(10) 4639(18)   -1024(23)                                                                             1.5(7)                                     H(3)     2892(10) 4704(18)   -2726(23)                                                                             1.9(7)                                     H(5)     3162(10) 2863(19)   -760(24)                                                                              1.9(7)                                     H(7)     3408(18) 5957(29)   -2513(42)                                                                             8.0(16)                                    H(7')    3733(16) 5540(28)   -3034(40)                                                                             7.6(16)                                    H(7")    3838(15) 5715(25)   -2097(34)                                                                             5.3(12)                                    H(8)     2271(14) 3644(26)   -1878(34)                                                                             5.0(12)                                    H(8')    2479(14) 2824(23)   -1891(30)                                                                             4.5(11)                                    H(8")    2446(13) 3411(24)   -2885(33)                                                                             4.3(10)                                    H(9)     4225(15) 3261(23)   -450(32)                                                                              5.2(11)                                    H(9')    3860(12) 2828(12)   166(27)                                                                               3.4(9)                                     H(9")    4018(12) 3693(22)   550(29)                                                                               3.7(9)                                     H(11N)   4093(11) 7169(18)   1975(25)                                                                              1.5(8)                                     H(13)    3060(10) 7177(18)   206(24)                                                                               1.9(7)                                     H(15)    3290(12) 8912(21)   2358(28)                                                                              3.7(9)                                     H(17)    3980(16) 6385(28)   24(34) 6.3(14)                                    H(17')   3562(12) 5949(22)   292(28)                                                                               3.4(9)                                     H(17")   3942(12) 5963(22)   1063(30)                                                                              3.7(10)                                    H(18)    2711(15) 8899(28)   521(38)                                                                               5.4(14)                                    H(18')   2529(17) 8840(33)   1444(42)                                                                              7.9(17)                                    H(18")   2430(23) 8122(39)   679(55)                                                                               12.6(24)                                   H(19)    3941(21) 8447(36)   3720(48)                                                                              10.1(23)                                   H(19')   4203(18) 8891(32)   2932(42)                                                                              8.1(16)                                    H(19")   4283(22) 8057(36)   3211(51)                                                                              10.8(23)                                   H(21N)   4426(12) 2570(22)   3345(27)                                                                              3.6(9)                                     H(23)    4616(12) 1014(21)   5637(29)                                                                              3.5(9)                                     H(25)    3563(10) 817(18)    3699(23)                                                                              1.4(6)                                     H(27)    5154(23) 2510(43)   4200(55)                                                                              13.2(28)                                   H(27')   5182(15) 2096(26)   5219(34)                                                                              5.5(13)                                    H(27")   4911(21) 2763(36)   5031(48)                                                                              9.9(20)                                    H(28)    4162(19) -374(32)   5226(39)                                                                              9.1(17)                                    H(28')   3675(16) -226(28)   5081(33)                                                                              6.3(13)                                    H(28")   3853(18) 148(33)    6073(41)                                                                              9.5(18)                                    H(29)    3490(18) 2375(30)   2599(43)                                                                              7.8(16)                                    H(29')   3594(14) 1703(25)   1928(33)                                                                              5.1(12)                                    H(29")   3917(19) 2361(33)   1981(43)                                                                              9.2(18)                                    ______________________________________                                    

EXAMPLE 4 Preparation of Tetraphenylphosphonium⁺ AlF₄ ⁻

Inside a nitrogen filled glove box, 0.225 g collidine H⁺ AlF₄ ⁻ prepared as in Example 3 was dissolved into 5 mL dry methanol and rapidly mixed with a second solution of 0.42 g tetraphenylphosphonium bromide also in 5 mL methanol. After 30 seconds the clear solution became progressively cloudy and large needle-like crystals of the desired compound began to precipitate from solution. Yield 0.33 g (74%). The material was recrystallized from hot acetone or acetonitrile to give x-ray quality crystals. IR (KBr) AlF₄ ⁻ at 787 cm⁻¹. NMR (CD₃ CN): ¹⁹ F, -194.6 ppm, 6 lines, J=38 Hz; Solid state ¹⁹ F MAS-NMR shows a single sharp resonance at -190 ppm. A single crystal grown from acetonitrile was used for a single crystal structure determination. Crystal data: PAlF₄ C₂₄ H₂₀ from acetonitrile, colorless, block, 0.26×0.26×0.50 mm, tetragonal, I₄ (#82), a=12.209(3), c=7.050(2) Å, T=-65° C., V=1050.9 Å³, Z=2, FW=442.38, Dc=1.398 g/cc, μ(Mo)=2.09 cm⁻¹.

All non-hydrogen atoms refined anisotropic, 88 parameters, data/parameter ratio=7.03, final R=0.041, Rw=0.044, error of fit=1.95. Atomic coordinates are listed in Table IV while the structure is depicted in FIG. 4. The structure shows only the two expected tetrahedral ions--the anion AlF₄ ⁻ (FIG. 4b) and the cation P(C₆ H₅)₄ ⁺ (FIG. 4a).

                  TABLE IV                                                         ______________________________________                                         Fractional Coordinates (X10000) and                                            Isotropic Thermal Parameters                                                   ATOM     X        Y          Z      BISO                                       ______________________________________                                         P(1)     0        0          0      2.3(1)'                                    Al(1)    0        5000       2500   3.1(1)'                                    F(1)     356(9)   4040(5)    1183(12)                                                                              21.7(4)'                                   C(1)     978(2)   669(2)     1511(4)                                                                               2.6(1)'                                    C(2)     2094(2)  458(2)     1376(4)                                                                               3.1(1)'                                    C(3)     2807(3)  984(3)     2624(6)                                                                               4.0(1)'                                    C(4)     2413(3)  1708(3)    3961(6)                                                                               4.3(1)'                                    C(5)     1299(3)  1930(3)    4065(5)                                                                               4.3(1)'                                    C(6)     583(2)   1390(3)    2855(4)                                                                               3.5(1)'                                    H(2)     2324(22) -8(23)     477(37)                                                                               1.8(5)                                     H(3)     3653(41) 747(36)    2457(90)                                                                              6.6(11)                                    H(4)     2898(29) 2109(27)   4867(64)                                                                              4.6(8)                                     H(5)     1017(32) 2384(37)   4849(90)                                                                              5.6(11)                                    H(6)     -218(29) 1484(30)   2771(62)                                                                              4.5(8)                                     ______________________________________                                    

EXAMPLE 5 Preparation of Tetraphenylarsonium⁺ AlF₄ ⁻

Inside a nitrogen filled glove box, 0.225 g collidineH⁺ AlF₄ ⁻ prepared as in Example 3 was dissolved in 5 mL dry methanol and rapidly mixed with a second solution of 0.42 g tetraphenylarsonium chloride also in 5 mL methanol. After 30 seconds the clear solution became progressively cloudy and large needle-like crystals of the desired compound began to precipitate from solution. Yield 0.43 g (88%). The material was recrystallized from hot acetone or acetonitrile to give x-ray quality crystals. IR (KBr) AlF₄ ⁻ at 788 cm⁻¹, NMR (0.002M in CD₃ CN); ¹⁹ F, -194.6 ppm, 6 lines, J=38 Hz; Solid state ¹⁹ F MAS-NMR shows a single sharp resonance at -190.1 ppm. A single crystal grown from acetone was used for a single crystal structure determination. Crystal data: AsAlF₄ C₂₄ H₂₀ from acetone, colorless, block. 0.30×0.26×0.47 mm, tetragonal, I₄ (#82), a=12.466(2), c=6.813(1) Å, T=-100° C. V=1058.8 Å³, Z=2, FW=486.32, Dc=1.525 g/cc, μ(Mo)=16.82 cm⁻¹.

All non-hydrogen atoms refined anisotropic, 88 parameters, data/parameter ration=7.78, final R=0.020, Rw=0.023, error of fit=1.24. Atomic coordinates are listed in Table V while the structure is depicted in FIG. 5. The structure shows only the two expected tetrahedral ions--the anion AlF₄ ⁻ (FIG. 5b) and the cation As(C₆ H₅)₄ ⁺ (FIG. 5a).

                  TABLE V                                                          ______________________________________                                         Fractional Coordinates (X10000) and                                            Isotropic Thermal Parameters                                                   ATOM     X        Y          Z      BISO                                       ______________________________________                                         As(1)    0        0          0      1.5(1)'                                    Al(1)    0        5000       2500   2.2(1)'                                    F(1)     160(4)   3953(3)    1161(6)                                                                               12.4(2)'                                   C(1)     1016(2)  713(2)     1645(3)                                                                               1.8(1)'                                    C(2)     2102(2)  454(2)     1562(3)                                                                               2.2(1)'                                    C(3)     2808(2)  972(2)     2826(4)                                                                               2.8(1)'                                    C(4)     2439(2)  1737(2)    4123(4)                                                                               3.0(1)'                                    C(5)     1358(2)  2010(2)    4174(4)                                                                               3.0(1)'                                    C(6)     637(2)   1482(2)    2952(4)                                                                               2.5(1)'                                    H(2)     2338(24) -21(23)    797(43)                                                                               2.2(5)                                     H(3)     3595(28) 652(29)    2673(61)                                                                              3.5(7)                                     H(4)     2871(24) 2138(22)   5247(66)                                                                              3.2(6)                                     H(5)     1057(25) 2548(25)   4928(95)                                                                              3.9(6)                                     H(6)     -139(25) 1729(24)   2957(42)                                                                              2.4(6)                                     ______________________________________                                    

EXAMPLE 6 Preparation of Tetraethylphosphonium⁺ AlF₄ ⁻

A mixture of 0.45 g PEt₄ ⁺ Br⁻ in 10 ml dry THF was treated with 0.42 g of KN(SiMe₃)₂ (Commercial, Aldrich) in a nitrogen atmosphere and was stirred 3 hours at room temperature. The resulting mixture was filtered, obtaining 0.24 g off-white solid which was discarded (theoretical yield of KBr, ca. 0.24 g). The solution was added to a suspension of 0.35 g pyridineH⁺ AlF₄ ⁻ in 10 ml dry pyridine in a nitrogen atmosphere and the mixture was stirred, soon becoming a pale yellow solution. After ca. 30 min the solution was evaporated to dryness and the residue recrystallized twice from CH₂ Cl₂, yield 0.12 g. IR (Nujol) 786 cm⁻¹, ¹ H NMR (CD₃ CN): 1.16 ppm, d (18 Hz) of t (8 Hz); 2.10 ppm, d (13 Hz) of q (8 Hz). ¹⁹ F NMR (CD₃ CN): -193 ppm, 6 lines, J=38 Hz, ²⁷ Al NMR (CD₃ CN): quintet, J=38 Hz.

C. H. anal. Calcd. C: 38.41, H: 8.06%. Found C: 37.83, 38.27; H: 8.11, 8.15%.

The reaction between P(C₂ H₅)₄ ⁺ Br⁻ and KN(Si(CH₃)₃)₂ in THF is well known to form KBr, the amine HN(Si(CH₃)₃)₂, and the ylid (C₂ H₅)₃ P═CHCH₃, and the ylid was not isolated for this Example.

In a related preparation, 0.55 g P(C₂ H₅)₄ ⁺ Br⁻ and 0.48 g KN(Si(CH₃)₃)₂ were stirred in 15 ml dry THF for 30 min, the mixture was filtered, and the solution added to 0.47 g pyridineH⁺ AlF₄ ⁻ in 10 ml pyridine, all in a nitrogen atmosphere. After stirring for several minutes the mixture became a solution which was evaporated; the residue was recrystallized from CH₂ Cl₂ /ether, yield 0.41 g (68%). IR, ¹ H and ¹⁹ F NMR as above.

EXAMPLE 7 Preparation of Triphenylmethylphosphonium⁺ AlF₄ ⁻

Inside a nitrogen filled glove box, 0.225 g collidineH⁺ AlF₄ ⁻ prepared as in Example 3 was dissolved into 5 mL dry methanol and rapidly mixed with a second solution of 0.36 g triphenylmethylphosphonium bromide also in 5 mL methanol. The clear solution was evaporated to dryness and the white powder was extracted into acetone leaving behind collidinium bromide which was removed by filtration. The clear acetone solution was evaporated to dryness forming colorless needle-shaped crystals of the desired material. Yield 0.23 g (61%). Thermal analysis of the crystals showed a single, sharp, weight loss event centered at 495° C. and a weight change corresponding exactly to the transformation to AlF₃. X-ray powder diffraction data are listed in Table VI and depicted in FIG. 6.

                  TABLE VI                                                         ______________________________________                                         Generator settings                                                                            40 kV, 30 mA                                                    CU alphal, 2 wavelengths                                                                      1.540598, 1.544435 Ang                                          Step size, sample time                                                                        0.020 deg, 0.50 s, 25.00 s/deg                                  Monochromator used                                                                            Yes                                                             Divergence slit                                                                               Automatic (specimen length: 12.5 mm)                            Peak angle range                                                                              2.000-60.000 deg                                                Peak position criterion                                                                       Centroid second derivative                                      Number of peaks in file                                                                       24 (Alphal: 21, Amorphous: 0)                                   ______________________________________                                         Peak Angle    Width   Peak Backg D spac                                                                               I/Imax                                                                               Type                              No.  (deg)    (deg)   (cts)                                                                               (cts) (Ang) (%)   A1  A2                            ______________________________________                                         1    5.290    1.92    10   6     16.7059                                                                              0     X   X                             2    10.145   0.16    961  27    8.7194                                                                               44    X   X                             3    14.408   0.12    1332 40    6.1479                                                                               61    X   X                             4    20.417   0.10    2200 95    4.3498                                                                               100   X   X                             5    20.532   0.10    1406 95    4.3257                                                                               64    X   X                             6    22.930   0.18    529  99    3.8786                                                                               24    X   X                             7    25.105   0.10    250  103   3.5472                                                                               11    X   X                             8    29.117   0.08    130  111   3.0669                                                                               6     X   X                             9    32.635   0.08    350  97    2.7417                                                                               16    X                                 10   32.728   0.08    454  97    2.7364                                                                               21    X   X                             11   32.865   0.04    182  97    2.7298                                                                               8         X                             12   34.145   0.06    144  95    2.6238                                                                               7     X                                 13   34.268   0.06    76   93    2.6212                                                                               3         X                             14   36.230   0.40    30   89    2.4795                                                                               1     X   X                             15   37.475   0.12    42   91    2.3999                                                                               2     X   X                             16   38.952   0.20    24   89    2.3122                                                                               1     X   X                             17   41.688   0.06    151  84    2.1666                                                                               7     X   X                             18   43.118   0.06    59   86    2.0980                                                                               3     X   X                             19   45.548   0.24    21   84    1.9916                                                                               1     X   X                             20   46.967   0.24    81   82    1.9347                                                                               4     X   X                             21   49.315   0.24    64   78    1.8479                                                                               3     X   X                             22   52.803   0.14    88   75    1.7338                                                                               4     X   X                             23   53.993   0.10    177  68    1.6969                                                                               8     X                                 24   54.143   0.06    102  68    1.6968                                                                               5         X                             ______________________________________                                    

EXAMPLE 8 Preparation of Tetraethylammonium⁺ AlF₄ ⁻

Inside a nitrogen filled glove box, 0.90 g collidineH⁺ AlF₄ ⁻ prepared as in Example 3 was dissolved in 10 mL warm methanol and then mixed with a second solution containing 0.66 g tetraethylammonium chloride dissolved in 10 mL methanol. After stirring for 15 mins the clear solution was evaporated to dryness and the white solid was placed in a horizontal tube furnace. The solid was heated to 300° C. in flowing nitrogen (50 cc/min) at 10° C. min and then held at 300° C. for 30 mins before cooling in nitrogen. The sample was then returned to the glove box and the solid was extracted into dry acetonitrile. The clear acetonitrile was evaporated to dryness leaving hygroscopic, clear, blocky crystals of the desired material. Yield 0.46 g (49%). Thermal analysis of these crystals shows a single, sharp, weight loss event centered at 400° C. and a weight change corresponding exactly to the transformation to AlF₃. X-ray powder diffraction data are listed in Table VII and depicted in FIG. 7. ¹⁹ F NMR (0.002M in CD₃ CN): ¹⁹ F, -194.6 ppm, 6 lines, J=38 Hz.

                  TABLE VII                                                        ______________________________________                                         Generator settings                                                                            40 kV, 30 mA                                                    CU alpha1, 2 wavelengths                                                                      1.540598, 1.544435 Ang                                          Step size, sample time                                                                        0.020 deg, 0.50 s, 25.00 s/deg                                  Monochromator used                                                                            Yes                                                             Divergence slit                                                                               Automatic (specimen length: 12.5 mm)                            Peak angle range                                                                              2.000-60.000 deg                                                Peak position criterion                                                                       Centroid second derivative                                      Number of peaks in file                                                                       11 (Alpha1: 11, Amorphous: 0)                                   ______________________________________                                         Peak Angle    Width   Peak Backg D spac                                                                               I/Imax                                                                               Type                              No.  (deg)    (deg)   (cts)                                                                               (cts) (Ang) (%)   A1  A2                            ______________________________________                                         1    7.715    1.92    10   11    11.4595                                                                              1     X   X                             2    16.077   0.06    1076 33    5.5129                                                                               97    X   X                             3    16.225   0.06    1076 33    5.4631                                                                               97    X   X                             4    16.332   0.06    1116 35    5.4274                                                                               100   X   X                             5    16.460   0.04    595  35    5.3856                                                                               54    X   X                             6    22.982   0.24    272  62    3.8698                                                                               24    X   X                             7    26.995   0.12    69   82    3.3030                                                                               6     X   X                             8    28.100   0.24    102  82    3.1756                                                                               9     X   X                             9    32.585   0.96    10   89    2.7480                                                                               1     X   X                             10   36.285   0.56    30   75    2.4759                                                                               3     X   X                             11   49.553   0.96    10   66    1.8396                                                                               1     X   X                             ______________________________________                                     

What is claimed is:
 1. A compound comprising the formula M^(+n) (AlF₄ ⁻)_(n) wherein M^(+n) is selected from the group consisting of N(R₂)₄, P(R₂)₄, As(R₂)₄, HN(R₂)₃, H₂ N(R₂)₂, H₃ N(R₂), (R₂)₃ P═N═P(R₂)₃, S N(R₂)₂ !₃, ##STR7## R is hydrogen, C₁ -C₁₀ linear or branched alkyl or aryl; R₂ is C₁ -C₁₀ linear or branched alkyl or aryl;n is 1; and k is 1 to 10;provided that M^(+n) is other than NMe₄ ⁺, NEt₄ ⁺, N(n-Bu)₄ ⁺, guanidinium (H₂ N═C(NH₂)₂)⁺ and pyridinium (C₅ H₆ N)⁺.
 2. A compound of the formula ZH⁺¹ (AlF₄ ⁻), where Z is selected from the group consisting of 1,8-bis(dimethylamino)napthalene; 2,4,6-trimethylpyridine; and 2,6-dimethylpyridine.
 3. The compound of claim 2, wherein Z is 1,8-bis(dimethylamino)napthalene.
 4. The compound of claim 2, wherein Z is 2,4,6-trimethylpyridine.
 5. The compound of claim 2, wherein Z is 2,6-dimethylpyridine.
 6. The compound of claim 1, wherein M^(+n) is ##STR8## where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl.
 7. The compound of claim 1, wherein M^(+n) is ##STR9## where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl.
 8. The compound of claim 1, wherein M^(+n) is ##STR10## where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl.
 9. The compound of claim 1, wherein M^(+n) is ##STR11## where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl.
 10. The compound of claim 1, wherein M^(+n) is (R)₂ N--(C(R)₂)_(k) --N(R)₃ ; where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl and k is 1-10.
 11. The compound of claim 1, wherein M^(+n) is X(R₂)₄, where X is selected from the group consisting of N, P and As; and R₂ is C₁ -C₁₀ linear or branched alkyl or aryl.
 12. The compound of claim 1, wherein M^(+n) is HN(R₂)₃, where R₂ is C₁ -C₁₀ linear or branched alkyl or aryl.
 13. The compound of claim 1, wherein M^(+n) is H₂ N(R₂)₂, where R₂ is C₁ -C₁₀ linear or branched alkyl or aryl.
 14. The compound of claim 1, wherein M^(+n) is H₃ N(R₂), where R₂ is C₁ -C₁₀ linear or branched alkyl or aryl.
 15. The compound of claim 1, wherein M^(+n) is (R₂)₃ P═N═P(R₂)₃, where R₂ is C₁ -C₁₀ linear or branched alkyl or aryl.
 16. The compound of claim 1, wherein M^(+n) is S N(R₂)₂ !₃, where R₂ is C₁ -C₁₀ linear or branched alkyl or aryl.
 17. The compound of claim 1, wherein M^(+n) is ##STR12## where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl and R₂ is C₁ -C₁₀ linear or branched alkyl or aryl.
 18. The compound of claim 1, wherein M^(+n) is ##STR13## where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl and R₂ is C₁ -C₁₀ linear or branched alkyl or aryl.
 19. The compound of claim 1, wherein M^(+n) is ##STR14## where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl.
 20. The compound of claim 1, wherein M^(+n) is ##STR15## where R is hydrogen or C₁ -C₁₀ linear or branched alkyl or aryl. 